Material for organic electroluminescence device and organic electroluminescence device

ABSTRACT

An organic electroluminescence device including an indenofluorenedione derivative represented by formula (I): 
                         
wherein X 1  and X 2 , which may be the same or different, are any of specific divalent groups; R 1  to R 10 , which may be the same or different, are a hydrogen atom, an alkyl group, and an aryl group, a heterocycle, a halogen atom, a fluoroalkyl group, an alkoxy group, an aryloxy group or a cyano group; and R 3  to R 6  or R 7  to R 10  may be bonded to each other to form a ring.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a Continuation of U.S. patent application Ser. No.13/185,283 filed Jul. 18, 2011, which is a Continuation of U.S. patentapplication Ser. No. 12/373,788, filed on Jan. 14, 2009, which is a 35U.S.C. §371 National Stage patent application of International patentapplication PCT/JP2008/062675, filed on Jul. 14, 2008, and claimspriority to Japanese patent application JP 2007-186912, filed on Jul.18, 2007.

TECHNICAL FIELD

The invention relates to a material for an organic electroluminescencedevice and an organic electroluminescence device.

BACKGROUND ART

An organic electroluminescence device (hereinafter the term“electroluminescence” is often abbreviated as “EL”) is a self-emissiondevice utilizing the principle that a fluorescent compound emits lightby the recombination energy of holes injected from an anode andelectrons injected from a cathode when an electric field is impressed.

Since C. W. Tang et al. of Eastman Kodak Co. reported a low-voltagedriven organic EL device in the form of a stacked type device, studieson organic EL devices wherein organic materials are used as theconstituting materials has actively been conducted.

The organic EL device reported by Tang et al. has a multilayer structurein which tris(8-hydroxyquinolinol) aluminum is used as an emitting layerand a triphenyldiamine derivative is used as a hole-transporting layer.The advantages of the multilayer structure include increased injectionefficiency of holes to the emitting layer, increased generationefficiency of excitons generated by recombination by blocking electronsinjected from the cathode, confinement of the generated excitons in theemitting layer, and so on.

As the multilayer structure of the organic EL device, a two-layered typeof a hole-transporting (injecting) layer and an electron-transportingemitting layer, and a three-layered type of a hole-transporting(injecting) layer, an emitting layer and an electron-transporting(injecting) layer are widely known. In such multilayer structuredevices, their device structures and fabrication methods have beencontrived to increase recombination efficiency of injected holes andelectrons.

Conventionally, aromatic diamine derivatives or aromatic condensed ringdiamine derivatives have been known as hole-transporting materials usedin the organic EL device.

However, in order to attain sufficient luminance in an organic EL devicein which these aromatic diamine derivatives are used as ahole-transporting material, problems such as shortened device life andincreased consumption power occur, since an applied voltage is requiredto be increased.

As the method to solve these problems, a method has been proposed inwhich an electron-acceptable compound such as Lewis acid is doped to thehole-injecting layer of the organic EL device (Patent Document Nos. 1 to7, or the like). However, the electron-accepting compound used in PatentDocument Nos. 1 to 4 suffers from a problem in which it becomes unstablewhen handling during the production process of the organic EL device orthe device life is shortened due to insufficient stability such as heatresistance at the time of driving of the organic EL device.

In addition, tetrafluorotetracyanoquinodimethane (TCNQF₄), which is anelectron-accepting compound exemplified in Patent Documents 3 and 5 to 7or the like, has a small molecular weight and is substituted withfluorine. Therefore, it has a high sublimation property, and may diffusewithin an apparatus when fabricating an organic EL device by vacuumvapor deposition, thereby contaminating the apparatus or the device.

-   Patent Document 1: JP-A-2003-031365-   Patent Document 2: JP-A-2001-297883-   Patent Document 3: JP-A-2000-196140-   Patent Document 4: JP-A-H11-251067-   Patent Document 5: JP-A-H4-297076-   Patent Document 6: JP-T-2004-514257-   Patent Document 7: US2005/0255334A1

The invention has been made based on the above-mentioned problems, andan object thereof is to provide an electron-acceptable material which issuitable as a material constituting an organic EL device.

DISCLOSURE OF THE INVENTION

As a result of intensive studies, the inventors noted anindenofluorenedione skeleton. Even when the quinone site thereof isconverted to a dicyanomethylene group or a cyanoimino group, thesecompounds suffer a small degree of steric hindrance, maintain theirmolecular planarity, are thermally stable, have a high sublimationtemperature, and are capable of producing an organic EL device by vapordeposition. Furthermore, due to the presence of two quinone sites in themolecule, they have a high degree of electron acceptability. Inaddition, by incorporating a specific substituent, electronacceptability can be enhanced or crystallinity can be changed. Forexample, since an unsubstituted indenofluorenedione skeleton has a highdegree of crystallinity, leak current may be generated due tocrystallization when the thickness is increased. Therefore, infabricating an organic EL device, crystallization can be suppressed byreducing the film thickness or by mixing with a hole-transportingmaterial such as an amine-based compound. If this compound is used in afilm with an increased thickness, or crystallization caused by thedevice fabrication conditions becomes problematic, a derivative of whichthe crystal condition has been changed by introducing into anindenofluorenedione skeleton a bulky substituent such as a phenyl groupcan be obtained.

The inventors have found that, if the indenofluorenedinone derivativesof the invention with the above-mentioned properties are used in anorganic EL device, in particular, in a hole-transporting layer, alowered driving voltage, prolonged device life and suppression ofincreases in voltage can be attained.

The invention can provide the following material for an organic ELdevice or the like.

1. A material for an organic electroluminescence device comprising anindenofluorenedione derivative shown by the following formula (I):

wherein X¹ and X², which may be the same or different, are any ofdivalent groups shown by the following formulas (a) to (e); R¹ to R¹⁰,which may be the same or different, are a hydrogen atom, an alkyl group,an aryl group, a heterocycle, a halogen atom, a fluoroalkyl group, analkoxy group, an aryloxy group or a cyano group; and R³ to R⁶ or R⁷ toR¹⁰ may be bonded to each other to form a ring;

wherein R⁵¹ to R⁵³, which may be the same or different, are a hydrogenatom, a fluoroalkyl group, an alkyl group, an aryl group or aheterocycle; and R⁵² and R⁵³ may be bonded to each other to form a ring.2. The material for an organic electroluminescence device according to1, wherein the indenofluorendione derivative contains at least one ofcompounds shown by the following formulas (IIa), (IIb), (IIc) or (III):

wherein R¹¹ to R⁵⁰, which may be the same or different, are a hydrogenatom, an alkyl group, an aryl group, a heterocycle, a fluorine atom, afluoroalkyl group, an alkoxy group, an aryloxy group or a cyano group,provided that a case where all of R¹¹ to R⁵⁰ are a hydrogen atom isexcluded; and R¹¹ to R⁵⁰ may be bonded to each other to form a ring.3. The material for an organic electroluminescence device according to 1or 2, which has a reduction potential in an acetonitrile solution of−1.0V or more (vsFc⁺/Fc; wherein Fc indicates ferrocene).4. The material for an organic electroluminescence device according toany one of 1 to 3, which is a hole-injecting material.5. An organic electroluminescence device comprising organic thin filmlayers between an anode and a cathode;

the organic thin film layers being a multilayer stack in which ahole-injecting layer, a hole-transporting layer, an emitting layer andan electron-transporting layer are stacked sequentially from the anode;and

the hole-injecting layer containing the material for an organicelectroluminescence device according to any one of 1 to 4.

6. The organic electroluminescence device according to 5, wherein thehole-injecting layer further contains a phenylenediamine compound shownby the following formula (IV):

wherein R⁶¹ to R⁶⁶, which may be the same or different, are a hydrogenatom, a halogen atom, a trifluoromethyl group, an alkyl group, an arylgroup or a heterocycle, or may form a naphthalene skeleton, a carbazoleskeleton or a fluorene skeleton with a phenyl group to which R⁶¹ to R⁶⁶bond; and n is 1 or 2.7. An indenofluorenedione derivative which is shown by the followingformula (I):

wherein X¹ and X², which may be the same or different, are any ofdivalent groups shown by the following formulas (a) to (e); and R¹ toR¹⁰, which may be the same or different, are a hydrogen atom, an alkylgroup, an aryl group, a heterocycle, a halogen atom, a fluoroalkylgroup, an alkoxy group, an aryloxy group or a cyano group; and R³ to R⁶or R⁷ to R¹⁰ may be bonded to each other to form a ring;

wherein R⁵¹ to R⁵³, which may be the same or different, are a hydrogenatom, a fluoroalkyl group, an alkyl group, an aryl group or aheterocyclic group; and R⁵² and R⁵³ may be bonded to each other to forma ring.8. The indenofluorenedione derivative according to 7, which is any ofcompounds shown by the following formulas (IIa), (IIb), (IIc) or (III):

where in R¹¹ to R⁵⁰, which may be the same or different, are a hydrogenatom, an alkyl group, an aryl group, a heterocycle, a fluorine atom, afluoroalkyl group, an alkoxy group, an aryloxy group or a cyano group,provided that a case where all of R¹¹ to R⁵⁰ are a hydrogen atom isexcluded; and R¹¹ to R⁵⁰ may be bonded to each other to form a ring.

According to the invention, it is possible to provide a novel materialfor an organic EL device. Also, it is possible to provide an organic ELdevice which can be driven at a low driving voltage and has a long life.

BRIEF DESCRIPTION OF THE INVENTION

FIG. 1 is a schematic cross-sectional view showing one embodiment of theorganic EL device of the invention.

BEST MODE FOR CARRYING OUT THE INVENTION

At first, the material for an organic EL device of the invention isdescribed.

The material for an organic EL device comprises an indenofluorenedionederivative shown by the following formula (I):

wherein X¹ and X², which may be the same or different, are any one ofdivalent groups shown by the following formulas (a) to (e); and R¹ toR¹⁰, which may be the same or different, are a hydrogen atom, an alkylgroup, an aryl group, a heterocycle, a halogen atom, a fluoroalkylgroup, an alkoxy group, an aryloxy group or a cyano group; and R³ to R⁶or R⁷ to R¹⁰ may be bonded to each other to form a ring;

wherein R⁵¹ to R⁵³, which may be the same or different, areindependently a hydrogen atom, a fluoroalkyl group, an alkyl group, anaryl group or a heterocyclic group; and R⁵² and R⁵³ may be bonded toeach other to form a ring.

As examples of the halogen atom shown by R¹ to R¹⁰, a fluorine atom, achlorine atom, a bromine atom or an iodine atom can be given.

Examples of the alkyl group include a methyl group, an ethyl group, ann-propyl group, an iso-propyl group, an n-butyl group, an iso-butylgroup, a tert-butyl group, a cyclopentyl group and a cyclohexyl group.

Examples of the aryl group include a phenyl group, a biphenyl group, anaphthyl group, a fluorophenyl group and a trifluoromethylphenyl group.

Examples of the fluoroalkyl group include a trifluoromethyl group, apentafluoroethyl group, a perfluorocyclohexyl group and aperfluouroadamantyl group.

Examples of the alkoxy group include a methoxy group, an ethoxy groupand a trifluoromethoxy group.

Examples of the aryloxy group include a benzyloxy group, apentafluorobenzyloxy group and a 4-trifluoromethylbenzyloxy group.

Examples of the heterocycle include pyridine, pyrazine, furane,imidazole, benzimidazole and thiophene.

Each of the alkyl group, aryl group, fluoroalkyl group or heterocycleshown by R¹ to R¹⁰ may be further substituted by a substituent. Thesesubstituents may be the same as the halogen atom, the cyano group, thealkyl group, the aryl group, the fluoroalkyl group or the heterocycle asmentioned above. The same can be applied to the fluoroalkyl group, thealkyl group, the aryl group or the heterocyclic group shown by R⁵¹ toR⁵³.

R³ to R⁶ or R⁷ to R¹⁰ may be bonded to each other to form a ring.Examples of the ring include a benzene ring, a naphthalene ring, apyrazine ring, a pyridine ring and a furan ring.

Similarly, R⁵² and R⁵³ may be bonded to each other to form a ring.

Due to the structure shown by the formula (I), stability such as theheat resistance and sublimation property or electron acceptability canbe enhanced. This compound has electron acceptability and improved heatresistance. Also, due to its capability of being purified throughsublimation, the purity thereof can be enhanced. By using the compoundin an organic EL device, driving voltage can be reduced and the life canbe prolonged. Furthermore, since the compound does not scatter insidethe film-forming apparatus during the production of a device, there isno fear that the film-forming apparatus or the organic EL device may becontaminated by the compound.

For the above-mentioned reason, the compound is suitable as the materialfor an organic EL device, in particular, as the hole-injecting material.

It is preferred that the compound shown by the above formula (I) be anycompounds shown by the following formulas (IIa), (IIb), (IIc) or (III).

wherein R¹¹ to R⁵⁰, which may be the same or different, areindependently a hydrogen atom, an alkyl group, an aryl group, aheterocycle, a fluorine atom, a fluoroalkyl group, an alkoxy group, anaryloxy group or a cyano group, provided that a case where all of R¹¹ toR⁵⁰ are a hydrogen atom is excluded; and R¹¹ to R⁵⁰ may be bonded toeach other to form a ring.

Examples of the alkyl group, the aryl group, the fluoroalkyl group, thealkoxy group, the aryloxy group or the heterocycle shown by R¹¹ to R⁵⁰are the same as those exemplified above for R¹ to R¹⁰.

Depending on the type of the substituent of X¹ and X² in the formula(I), isomers are present. For example, in the case of the compound shownby the formula (IIa), the isomers (IIb) (IIc) are present which havedifferent bonding positions of the two cyano groups of the cyanoiminegroups. The material of the invention is not restricted to a specificisomer. It may be a compound having no isomers, a syn-type isomer, ananti-type isomer, or a mixture thereof.

It is preferred that the material for an organic EL device of theinvention have a reduction potential in an acetonitrile solution of−1.0V (vsFc⁺/Fc) or more, particularly preferably −0.8V (vsFc⁺/Fc) ormore. Here, Fc indicates ferrocene. Electron acceptability is furtherincreased by using a compound with a reduction potential of −1.0V ormore.

An increase in electron-acceptability has the following merits. Electrontransfer with an anode formed of ITO or a material having a workfunction smaller than that of ITO is facilitated. In addition, since theHOMO level of a hole-transporting material and the LUMO level of anelectron-transporting material get close to each other, holes can beinjected more easily.

Specific examples of the material for an organic EL device of theinvention will be shown below.

The indenofluorenedione derivative of the invention can be obtained bythe synthesis of the following scheme 1 from an indenofluorenedionederivative which has been synthesized by the synthesis method described,for example, in Organic Letters Vol. 4, page 2157 (2002) or in OrganicLetters Vol. 7, page 4229 (2005). For the details such as synthesisconditions, reference can be made to Liebigs Ann. Chem. (1986), page142. By subjecting crystals obtained by these reactions to purificationby sublimation to decrease the amount of impurities, the crystals canattain excellent performance in respect of device life or the like whenused as the material for an organic EL device.

R¹ to R¹⁰ are the same as in the above formula (I).

Next, the organic EL device of the invention is described.

The organic EL device of the invention has organic thin film layersbetween the anode and the cathode. Organic thin film layers include ahole-injection layer, a hole-transporting layer, an emitting layer andan electron-transporting layer in this order, and the hole-injectinglayer contains the material for an organic EL device of the invention.

FIG. 1 is a schematic cross-sectional view showing one embodiment of theorganic EL device of the invention.

In an organic EL device 1, an anode 10, a hole-injecting layer 20, ahole-transporting layer 30, an emitting layer 40, anelectron-transporting layer 50 and a cathode 60 are sequentially stackedon a substrate (not shown). In this device, organic thin film layers areof a multilayer structure comprising the hole-injecting layer 20, thehole-transporting layer 30, the emitting layer 40 and theelectron-transporting layer 50. In the invention, the hole-injectinglayer 20 contains the material for an organic EL device of theinvention. As a result, the organic EL device can be driven at a lowervoltage and has a prolonged device life. In addition, a voltage increasecan be suppressed.

Other organic layers than the hole-injecting layer may contain thematerial for an organic EL device of the invention. In this case, thematerial for an organic EL device of the invention may be used inmixture with materials constituting each layer, which will be mentionedlayer.

The content of the material for an organic EL device of the invention inthe hole-injecting layer is preferably 1 to 100 mole %.

In the organic EL device of the invention, it is preferred that thehole-injecting layer contain a phenylenediamine compound shown by thefollowing formula (IV), in addition to the compounds shown by (I),(IIa), (IIb), (IIc) or (III) as mentioned above.

wherein R⁶¹ to R⁶⁶, which may be the same or different, areindependently a hydrogen atom, a halogen atom, trifluoromethyl group, analkyl group, an aryl group or a heterocycle, or may form a naphthaleneskeleton, a carbazole skeleton or a fluorene skeleton with a phenylgroup to which R⁶¹ to R⁶⁶ bond; and n is 1 or 2.

When the phenylenediamine compound is contained, uniformity of a film,heat resistance or carrier-injecting properties may be improved ascompared with the case where the compound of the invention is usedsingly.

In the formula (IV), as the halogen atom shown by R⁶¹ to R⁶⁶, a fluorineatom is preferable.

As the alkyl group shown by R⁶¹ to R⁶⁶, a methyl group, an isopropylgroup, a tert-butyl group and a cyclohexyl group are preferable, forexample.

As the aryl group shown by R⁶¹ to R⁶⁶, a phenyl group, a naphthyl groupand a fluorenyl group are preferable, for example. They may besubstituted with a methyl group or the like.

As the heterocycle shown by R⁶¹ to R⁶⁶, a pyridine ring and a pyrazinering are preferable, for example.

R⁶¹ to R⁶⁶ may form a naphthalene skeleton, a carbazole skeleton or afluorene skeleton with a bonded phenyl group. They may be substitutedwith a methyl group or the like.

The content of the compound shown by the formula (IV) in thehole-injecting layer is preferably 0.1 to 98 mole %.

The mixing ratio of the compound shown by the above-mentioned formula(I), (IIa), (IIb), (IIc) or (III) and the phenylenediamine compoundshown by the formula (IV) may be selected appropriately according to thematerial of the anode.

Preferred examples of the compound (IV) are given below.

The material for the organic EL device of the invention can be used fora device with a configuration other than that in the above-mentionedembodiment. For example, the material for the organic EL device of theinvention may be used as a material for each organic layer such as anemitting layer constituting a device with the following configurations(1) to (15).

(1) Anode/emitting layer/cathode

(2) Anode/hole-transporting layer/emitting layer/cathode

(3) Anode/emitting layer/electron-transporting layer/cathode

(4) Anode/hole-transporting layer/emitting layer/electron-transportinglayer/cathode

(5) Anode/hole-transporting layer/emitting layer/adhesion-improvinglayer/cathode

(6) Anode/hole-injecting layer/hole-transporting layer/emittinglayer/electron-transporting layer/cathode (FIG. 1)

(7) Anode/hole-transporting layer/emitting layer/electron-transportinglayer/electron-injecting layer/cathode

(8) Anode/hole-injecting layer/hole-transporting layer/emittinglayer/electron-transporting layer/electron-injecting layer/cathode

(9) Anode/insulating layer/hole-transporting layer/emittinglayer/electron-transporting layer/cathode

(10) Anode/hole-transporting layer/emitting layer/electron-transportinglayer/insulating layer/cathode

(11) Anode/inorganic semiconductor layer/insulatinglayer/hole-transporting layer/emitting layer/insulating layer/cathode

(12) Anode/insulating layer/hole-transporting layer/emittinglayer/electron-transporting layer/insulating layer/cathode

(13) Anode/hole-injecting layer/hole-transporting layer/emittinglayer/electron-transporting layer/insulating layer/cathode

(14) Anode/insulating layer/hole-injecting layer/hole-transportinglayer/emitting layer/electron-transporting layer/electron-injectinglayer/cathode

(15) Anode/insulating layer/hole-injecting layer/hole-transportinglayer/emitting layer/electron-transporting layer/electron-injectinglayer/insulating layer/cathode

Among these, usually, the configurations (4), (6), (7), (8), (12), (13)and (15) are preferably used.

Each member constituting the organic EL device of the invention will bedescribed below.

(Transparent Substrate)

The organic EL device is usually formed on a transparent substrate. Thetransparent substrate is a substrate for supporting the organic ELdevice, and is preferably a flat and smooth substrate having a400-to-700-nm-visible-light transmittance of 50% or more.

Specific examples thereof include glass plates and polymer plates.Examples of the glass plate include soda-lime glass,barium/strontium-containing glass, lead glass, aluminosilicate glass,borosilicate glass, barium borosilicate glass, and quartz. Examples ofthe polymer plate include polycarbonate, acrylic polymer, polyethyleneterephthalate, polyethersulfide, and polysulfone.

Transparency is not required when the supporting substrate is positionedin the direction opposite to the light-outcoupling direction.

(Anode)

The anode of the organic EL device plays a role for injecting holes intoits hole-transporting layer or emitting layer. When transparency isrequired for the anode, indium tin oxide alloy (ITO), tin oxide (NESA),indium zinc oxide alloy (IZO), gold, silver, platinum, copper, and thelike may be used as the material for the anode. When a reflectiveelectrode which does not require transparency is used, in addition tothose metals, a metal such as aluminum, molybdenum, chromium, and nickelor alloys thereof may also be used.

Even when the anode with a small work function (for example, 5.0 eV orless) and the hole-injecting layer using the material for the organic ELdevice of the invention are used in combination, electron transfer ispossible and the hole-injecting layer shows good injection properties.

These materials may be used singly, or alloys of these materials or amaterial to which other elements are added may be selected appropriatelyand used.

The anode can be prepared by forming a thin film using these electrodematerials by a method such as the vapor deposition method or thesputtering method.

In the case where emission from the emitting layer is taken out throughthe anode, the transmittance of the anode to the emission is preferablymore than 10%. The sheet resistance of the anode is preferably severalhundred Ω/□ or less. The film thickness of the anode, which variesdepending upon the material thereof, is usually from 1 nm to 1 μm,preferably from 10 to 200 nm.

(Emitting Layer)

The emitting layer of the organic EL device has the following functions(1), (2) and (3) in combination.

(1) Injection function: function of allowing injection of holes from theanode or hole-injecting layer and injection of electrons from thecathode or electron-injecting layer upon application of an electricfield

(2) Transporting function: function of moving injected carriers(electrons and holes) due to the force of an electric field

(3) Emitting function: function of allowing electrons and holes torecombine therein to emit light

Note that electrons and holes may be injected into the emitting layerwith different degrees, or the transportation capabilities indicated bythe mobility of holes and electrons may differ. It is preferable thatthe emitting layer move either electrons or holes.

As the method for forming the emitting layer, a known method such asdeposition, spin coating, or an LB method may be applied. It ispreferable that the emitting layer be a molecular deposition film. Here,the molecular accumulation film means a thin film formed by depositionof a material compound in a vapor phase or a film formed bysolidification of a material compound which is in a solution state or ina liquid state. The molecular deposition film is distinguished from athin film (molecular accumulation film) formed using the LB method bythe difference in aggregation structure or higher order structure or thedifference in function due to the difference in structure.

The emitting layer may also be formed by dissolving a binder such as aresin and a material compound in a solvent to obtain a solution, andforming a thin film from the solution by spin coating or the like, asdisclosed in JP-A-57-51781.

In the invention, if need arises, known emitting materials other thanthe emitting materials formed of the novel compound of the invention maybe contained in the emitting layer insofar as the object of theinvention is not impaired. An emitting layer containing other knownemitting materials may be stacked on the emitting layer containing theemitting materials formed of the novel compound of the invention.

As the emitting material or the doping material used for the emittinglayer, anthracene, naphthalene, phenanthrene, pyrene, tetracene,coronene, chrysene, fluorescein, perylene, phthaloperylene,naphthaloperylene, perynone, phthaloperynone, naphthaloperynone,diphenylbutadiene, tetraphenylbutadiene, coumarin, oxadiazole, aldazine,bisbenzoxazoline, bisstyryl, pyrazine, cyclopentadiene, a quinolinemetal complex, an aminoquinoline metal complex, a benzoquinoline metalcomplex, imine, diphenylethylene, vinylanthracene, diaminocarbazol,pyran, thiopyran, polymethine, merocyanine, an imidazole chelate oxanoidcompound, quinacridone, rubrene, a fluorescent pigment and like can begiven. Note that the emitting material and the doping material are notlimited to these compounds.

As the host material for use in the emitting layer, the compounds shownby the following formulas (i) to (ix) are preferred.

Asymmetrical anthracene shown by the following formula (i):

wherein Ar is a substituted or unsubstituted condensed aromatic grouphaving 10 to 50 carbon atoms forming a ring (hereinafter referred to asa “ring carbon atom”),

Ar′ is a substituted or unsubstituted aromatic group having 6 to 50 ringcarbon atoms,

X³ to X⁵ are independently a substituted or unsubstituted aromatic grouphaving 6 to 50 ring carbon atoms, a substituted or unsubstitutedaromatic heterocyclic group having 5 to 50 atoms forming a ring(hereinafter referred to as a “ring atom”), a substituted orunsubstituted alkyl group having 1 to 50 carbon atoms, a substituted orunsubstituted alkoxy group having 1 to 50 carbon atoms, a substituted orunsubstituted aralkyl group having 6 to 50 carbon atoms, a substitutedor unsubstituted aryloxy group having 5 to 50 ring atoms, a substitutedor unsubstituted arylthio group having 5 to 50 ring atoms, a substitutedor unsubstituted alkoxycarbonyl group having 1 to 50 carbon atoms, acarboxyl group, a halogen atom, a cyano group, a nitro group or ahydroxyl group.

a, b and c are each an integer of 0 to 4.

n is an integer of 1 to 3. When n is 2 or more, the anthracene in [ ]may be the same or different.

Asymmetrical monoanthracene derivatives shown by the following formula(ii):

wherein Ar¹ and Ar² are independently a substituted or unsubstitutedaromatic ring group having 6 to 50 ring carbon atoms, and in and n areeach an integer of 1 to 4, provided that in the case where m=n=1 and Ar¹and Ar² are symmetrically bonded to the benzene rings, Ar¹ and Ar² arenot the same, and in the case where m or n is an integer of 2 to 4, m isdifferent from n.

R⁷¹ to R⁸⁰ are independently a hydrogen atom, a substituted orunsubstituted aromatic ring group having 6 to 50 ring carbon atoms, asubstituted or unsubstituted aromatic hetrocyclic group having 5 to 50ring atoms, a substituted or unsubstituted alkyl group having 1 to 50carbon atoms, a substituted or unsubstituted cycloalkyl group, asubstituted or unsubstituted alkoxy group having 1 to 50 carbon atoms, asubstituted or unsubstituted aralkyl group having 6 to 50 carbon atoms,a substituted or unsubstituted aryloxy group having 5 to 50 ring atoms,a substituted or unsubstituted arylthio group having 5 to 50 ring atoms,a substituted or unsubstituted alkoxycarbonyl group having 1 to 50carbon atoms, a substituted or unsubstituted silyl group, a carboxylgroup, a halogen atom, a cyano group, a nitro group or a hydroxyl group.

Asymmetrical pyrene derivatives shown by the following formula (iii)

wherein Ar³ and Ar⁴ are independently a substituted or unsubstitutedaromatic group having 6 to 50 ring carbon atoms;

L¹ and L² are each a substituted or unsubstituted phenylene group, asubstituted or unsubstituted naphthalenylene group, a substituted orunsubstituted fluolenylene group, or a substituted or unsubstituteddibenzosilolylene group;

m is an integer of 0 to 2, n is an integer of 1 to 4, s is an integer of0 to 2, and t is an integer of 0 to 4;

L¹ or Ar³ bonds at any one position of 1 to 5 of the pyrene, and L² orAr⁴ bonds at any one position of 6 to 10 of the pyrene; provided thatwhen n+t is an even number, Ar³, Ar⁴, L¹ and L² satisfy the following(1) and (2):

(1) Ar³≠Ar⁴ and/or L¹≠L² where ≠ means these substituents are groupshaving different structures from each other.

(2) When Ar³=Ar⁴ and L¹=L²,

(2-1) m≠s and/or n≠t, or

(2-2) when m=s and n=t,

(2-2-1) when L¹ and L² or pyrene are independently bonded to differentbonding positions of Ar³ and Ar⁴, (2-2-2) when L¹ and L² or pyrene arebonded to the same position of Ar³ and Ar⁴, the position of thesubstitution of L¹ and L² or Ar³ and Ar⁴ at pyrene are not necessarilybe the 1^(st) position and the 6^(th) position, or the 2^(nd) positionand the 7^(th) position.

Asymmetrical anthracene shown by the following formula (iv):

wherein A¹ and A² are independently a substituted or unsubstitutedcondensed aromatic ring group having 10 to 20 ring carbon atoms,

Ar⁵ and Ar⁶ are independently a hydrogen atom or a substituted orunsubstituted aromatic ring group with 6 to 50 ring carbon atoms,

R⁸¹ to R⁹⁰ are independently a hydrogen atom, a substituted orunsubstituted aromatic ring group having 6 to 50 ring carbon atoms, asubstituted or unsubstituted aromatic heterocyclic group having 5 to 50ring atoms, a substituted or unsubstituted alkyl group having 1 to 50carbon atoms, a substituted or unsubstituted cycloalkyl group, asubstituted or unsubstituted alkoxy group having 1 to 50 carbon atoms, asubstituted or unsubstituted aralkyl group having 6 to 50 carbon atoms,a substituted or unsubstituted aryloxy group having 5 to 50 ring atoms,a substituted or unsubstituted arylthio group having 5 to 50 ring atoms,a substituted or unsubstituted alkoxycarbonyl group having 1 to 50carbon atoms, a substituted or unsubstituted silyl group, a carboxylgroup, a halogen atom, a cyano group, a nitro group or a hydroxyl group,

and each of Ar⁵, Ar⁶, R⁸⁹ and R⁹⁰ may be plural, and adjacent groupsthereof may form a saturated or unsaturated ring structure, providedthat groups do not symmetrically bond to 9 and 10 positions of thecentral anthracene with respect to X-Y axis.

Anthracene derivative shown by the following formula (v)

wherein R⁹¹ to R¹⁰⁰ are independently a hydrogen atom, an alkyl group, acycloalkyl group, an aryl group which may be substituted, an alkoxygroup, an aryloxy group, an alkylamino group, an alkenyl group, anarylamino group or a heterocyclic group which may be substituted; a andb are each an integer of 1 to 5; when they are 2 or more, R⁹¹s or R⁹²smay be the same or different, or R⁹¹s or R⁹²s may be bonded together toform a ring; R⁹³ and R⁹⁴, R⁹⁵ and R⁹⁶, R⁹⁷ and R⁹⁸, or R⁹⁹ and R¹⁰⁰ maybe bonded together to form a ring; and L³ is a single bond, —O—, —S—,—N(R)— (R is an alkyl group or a substituted or unsubstituted arylgroup), an alkylene group or an arylene group.Anthracene derivative shown by the following formula (vi):

wherein R¹⁰¹ to R¹¹⁰ are independently a hydrogen atom, an alkyl group,a cycloalkyl group, an aryl group, an alkoxy group, an aryloxy group, analkylamino group, an arylamino group or a heterocyclic group which maybe substituted; c, d, e and f are each an integer of 1 to 5; when theyare 2 or more, R¹⁰¹s R¹⁰²s, R¹⁰⁶s or R¹⁰⁷s may be the same or different,R¹⁰¹s, R¹⁰²s, R¹⁰⁶s or R¹⁰⁷s may be bonded to each other to form a ring,or R¹⁰³ and R¹⁰⁴, or R¹⁰⁸ and R¹⁰⁹ may be bonded to each other to form aring; L⁴ is a single bond, —O—, —S—, —N(R)— (R is an alkyl group or asubstituted or unsubstituted aryl group), an alkylene group or anarylene group.

Spirofluorene derivatives shown by the following formula (vii):

wherein A⁵ to A⁸ are independently a substituted or unsubstitutedbiphenyl group or a substituted or unsubstituted naphthyl group.Condensed ring-containing compounds shown by the following formula(viii):

wherein A⁹ to A¹⁴ are the same as the above-described ones and R¹¹¹ toR¹¹³ are independently a hydrogen atom, alkyl group having 1 to 6 carbonatoms, cycloalkyl group having 3 to 6 carbon atoms, alkoxy group having1 to 6 carbon atoms, aryloxy group having 5 to 18 carbon atoms,aralkyloxy group having 7 to 18 carbon atoms, arylamino group having 5to 16 carbon atoms, nitro group, cyano group, ester group having 1 to 6carbon atoms, or a halogen atom, provided that at least one of A⁹ to A¹⁴is a group having a condensed aromatic ring with three or more rings.Fluorene compound shown by the following formula (ix):

wherein R¹¹⁴ and R¹¹⁵ are a hydrogen atom, a substituted orunsubstituted alkyl group, substituted or unsubstituted aralkyl group,substituted or unsubstituted aryl group, substituted or unsubstitutedheterocyclic group, substituted amino group, cyano group, or a halogenatom; R¹¹⁴s bonded to different fluorene groups may be the same ordifferent, and R¹¹⁴ and R¹¹⁵ bonded to a single fluorene group may bethe same or different, R¹¹⁶ and R¹¹⁷ are a hydrogen atom, a substitutedor unsubstituted alkyl group, substituted or unsubstituted aralkylgroup, substituted or unsubstituted aryl group, or substituted orunsubstituted heterocyclic group, provided that R¹¹⁶s or R¹¹⁷s bonded todifferent fluorene groups may be the same or different, and R¹¹⁶ andR¹¹⁷ bonded to a single fluorene group may be the same or different; Ar⁷and Ar⁸ are a substituted or unsubstituted condensed polycyclic aromaticgroup with a total number of benzene rings of three or more or acondensed polycyclic heterocyclic group which is bonded to the fluorenegroup through substituted or unsubstituted carbon and has a total numberof benzene rings and heterocyclic rings of three or more, provided thatAr⁷ and Ar⁸ may be the same or different; and n is an integer of 1 to10.

Among the above-mentioned host materials, the anthracene derivative ispreferable, and the monoanthracene derivative is more preferable withthe asymmetrical anthracene being particularly preferable.

Phosphorescent compounds can be used as an emitting material. When usinga phosphorescent compound, compounds containing a carbazole ring arepreferred for a host material. A dopant is a compound that can emitlight from triplet excitons. The dopant is not limited so long as it canemit light from triplet excitons, but it is preferably a metal complexcontaining at least one metal selected from the group of Ir, Ru, Pd, Pt,Os and Re. A porphyrin metal complex or an ortho-metalated metal complexis preferable.

The compounds containing a carbazole ring, which are a host suitable forphosphorescence emission, is a compound which allows a phosphorescentcompound to emit as a result of energy transfer from its excited stateto the phosphorescent compound. The host compound is not limited so longas the compound can transfer its excited energy to a phosphorescentcompound and it can be selected depending on purposes. The host compoundmay contain any heterocyclic ring other than a carbazole ring.

Specific examples of the host compounds include carbazole, triazole,oxazole, oxadiazole, imidazole, polyarylalkane, pyrazoline, pyrazolone,phenylenediamine, arylamine, amino-substituted calcone, styrylanthracene, fluorenone, hydrazone, stilbene and silazane derivatives;aromatic tertiary amine, styrylamine, aromatic dimethylidene andporphyrin compounds; anthraquinodimethane, anthrone, diphenylquinone,thiopyrandioxide, carbodiimide, fluoreniridenemethane anddistyrylpyrazine derivatives; heterocyclic tetracarboxylic anhydridessuch as naphthaleneperylene; phthalocyanine derivatives; metal complexesof 8-quinolinol derivatives; various metal complex polysilane compoundsshown by metal complexes having metalphthalocyanine, benzoxazole orbenzothiaole as a ligand; electroconductive macromolecular oligomerssuch as poly(N-vinylcarbazole) derivatives, aniline copolymers,thiophene oligomers and polythiophene; and macromolecular compounds suchas polythiophene, polyphenylene, polyphenylenevinylene and polyfluorenederivatives. Host compounds can be used individually or as a combinationof two or more kinds.

Specific compounds shown below can be exemplified.

A phosphorescent dopant is a compound that can emit light from tripletexcitons. The dopant is not limited so long as it can emit light fromtriplet excitons, but it is preferably a metal complex containing atleast one metal selected from the group of Ir, Ru, Pd, Pt, Os and Re. Aporphyrin metal complex or an ortho-metalated metal complex ispreferable. As a porphyrin metal complex, a porphyrin platinum complexis preferable. The phosphorescent compounds can be used individually oras a combination of two or more kinds.

There are various ligands forming an ortho-metalated metal complex.Preferable ligands include 2-phenylpyridine, 7,8-benzoquinoline,2-(2-thienyl)pyridine, 2-(1-naphtyl)pyridine and 2-phenylquinolinederivatives. These derivatives may have substituents, if necessary.Fluorides and derivatives with a trifluoromethyl group introduced areparticularly preferable as a blue dopant. As an auxiliary ligand,ligands other than the above-mentioned ligands, such as acetylacetonateand picric acid may be contained.

The content of a phosphorescent dopant in an emitting layer is notlimited and can be properly selected according to purposes; for example,it is 0.1 to 70 mass %, preferably 1 to 30 mass %. When the content of aphosphorescent compound is less than 0.1 mass %, emission may be weakand the advantages thereof may not be sufficiently obtained. When thecontent exceeds 70 mass %, the phenomenon called concentration quenchingmay significantly proceed, thereby degrading the device performance.

The emitting layer may contain hole-transporting materials,electron-transporting materials and polymer binders, if necessary.

The thickness of an emitting layer is preferably from 5 to 50 nm, morepreferably from 7 to 50 nm and most preferably from 10 to 50 nm. When itis less than 5 nm, the formation of an emitting layer and the adjustmentof chromaticity may become difficult. When it exceeds 50 nm, the drivingvoltage may increase.

(Hole-Transporting Layer:Hole-Injecting Layer)

The hole-transporting layer is a layer for helping the injection ofholes into the emitting layer so as to transport holes to an emittingregion. The hole mobility thereof is large and the ionization energythereof is usually as small as 5.5 eV or less. Such a hole-transportinglayer is preferably made of a material which can transport holes to theemitting layer at a low electric field intensity. In addition, forexample, it is preferred that the hole mobility be at least 10⁻⁴cm²/V·sec when an electric field of 10⁴ to 10⁶V/cm is impressed.

Specific examples of materials for a hole-transporting layer includetriazole derivatives (see U.S. Pat. No. 3,112,197 and others),oxadiazole derivatives (see U.S. Pat. No. 3,189,447 and others),imidazole derivatives (see JP-B-37-16096 and others), polyarylalkanederivatives (see U.S. Pat. Nos. 3,615,402, 3,820,989 and 3,542,544,JP-B-45-555 and 51-10983, JP-A-51-93224, 55-17105, 56-4148, 55-108667,55-156953 and 56-36656, and others), pyrazoline derivatives andpyrazolone derivatives (see U.S. Pat. Nos. 3,180,729 and 4,278,746,JP-A-55-88064, 55-88065, 49-105537, 55-51086, 56-80051, 56-88141,57-45545, 54-112637 and 55-74546, and others), phenylene diaminederivatives (see U.S. Pat. No. 3,615,404, JP-B-51-10105, 46-3712 and47-25336, and 54-119925, and others), arylamine derivatives (see U.S.Pat. Nos. 3,567,450, 3,240,597, 3,658,520, 4,232,103, 4,175,961 and4,012,376, JP-B-49-35702 and 39-27577, JP-A-55-144250, 56-119132 and56-22437, DE1,110,518, and others), amino-substituted chalconederivatives (see U.S. Pat. No. 3,526,501, and others), oxazolederivatives (ones disclosed in U.S. Pat. No. 3,257,203, and others),styrylanthracene derivatives (see JP-A-56-46234, and others), fluorenonederivatives (JP-A-54-110837, and others), hydrazone derivatives (seeU.S. Pat. No. 3,717,462, JP-A-54-59143, 55-52063, 55-52064, 55-46760,57-11350, 57-148749 and 2-311591, and others), stilbene derivatives (seeJP-A-61-210363, 61-228451, 61-14642, 61-72255, 62-47646, 62-36674,62-10652, 62-30255, 60-93455, 60-94462, 60-174749 and 60-175052, andothers), silazane derivatives (U.S. Pat. No. 4,950,950), polysilanes(JP-A-2-204996), aniline copolymers (JP-A-2-282263), andelectroconductive high molecular oligomers (in particular thiopheneoligomers).

In addition to the hole-transporting layer, in order to help theinjection of holes, it is preferred that the hole-injecting layer beprovided separately. As the material for the hole-injecting layer, theorganic EL material of the invention may be used singly or incombination with other materials. As the other materials, the samematerials as used for the hole-transporting layer or the compoundsexemplified by the above-mentioned formula (IV) can be used. Thefollowing can also be used: porphyrin compounds (disclosed inJP-A-63-295695 and others), aromatic tertiary amine compounds andstyrylamine compounds (see U.S. Pat. No. 4,127,412, JP-A-53-27033,54-58445, 55-79450, 55-144250, 56-119132, 61-295558, 61-98353 and63-295695, and others).

The following can also be given as examples:4,4′-bis(N-(1-naphthyl)-N-phenylamino)biphenyl (NPD), which has in themolecule thereof two condensed aromatic rings, disclosed in U.S. Pat.No. 5,061,569, and4,4′,4″-tris(N-(3-methylphenyl)-N-phenylamino)triphenylamine (MTDATA),wherein three triphenylamine units are linked in a star-burst form,disclosed in JP-A-4-308688.

Inorganic compounds such as p-type Si and p-type SiC as well as aromaticdimethylidene type compounds can also be used as the material of thehole-injecting layer.

The hole-injecting layer or the hole-transporting layer can be formed,for example, from the above-mentioned compounds by a known method suchas vacuum deposition, spin coating, casting or LB technique. The filmthickness of the hole-injecting layer and hole-transporting layer is notparticularly limited, and is usually from 1 nm to 5 μm. Thehole-injecting layer or hole-transporting layer may be a single layermade of one or two or more of the above-mentioned materials, or may bestacked hole-injecting layers or hole-transporting layers made ofdifferent compounds, insofar as the compound of the invention iscontained in the hole-transporting region.

An organic semiconductor layer is one type of a hole-transporting layerfor helping the injection of holes or electrons into an emitting layer,and is preferably a layer having an electric conductivity of 10⁻¹⁰ S/cmor more. As the material of such an organic semiconductor layer,electroconductive oligomers such as thiophene-containing oligomers orarylamine-containing oligomers disclosed in JP-A-8-193191, andelectroconductive dendrimers such as arylamine-containing dendrimers maybe used.

(Electron-Injecting/Transporting Layer)

The electron-injecting/transporting layer is a layer which assistsinjection of electrons into the emitting layer and transports electronsto the emitting region, and exhibits a high degree of electron mobility.An adhesion-improving layer is formed of a material which exhibitsexcellent adhesion to the cathode.

The thickness of the electron-transporting layer is arbitrarily selectedin the range of several nanometers to several micrometers. When theelectron-transporting layer has a large thickness, it is preferable thatthe electron mobility be at least 10⁻⁵ cm²/Vs or more at an appliedelectric field of 10⁴ to 10⁶ V/cm in order to prevent an increase involtage.

The material used in the electron-transporting layer is preferably ametal complex of 8-hydroxyquinoline or a derivative thereof or anoxadiazole derivative. As specific examples of 8-hydroxyquinoline and ametal complex of an 8-hydroxyquinoline derivative, metal chelate oxinoidcompounds including a chelate of oxine (8-quinolinol or8-hydroxyquinoline) can be given.

An electron-transporting compound of the following general formula canbe given as the oxadiazole derivative.

wherein Ar¹¹, Ar¹², Ar¹³, Ar¹⁵, Ar¹⁶ and Ar¹⁹ are independentlysubstituted or unsubstituted aryl groups and may be the same ordifferent. Ar¹⁴, Ar¹⁷ and Ar¹⁸ are independently substituted orunsubstituted arylene groups and may be the same or different.

As examples of the aryl group, a phenyl group, a biphenyl group, ananthryl group, a perylenyl group, and a pyrenyl group can be given. Asexamples of the arylene group, a phenylene group, a naphthylene group, abiphenylene group, an anthrylene group, a perylenylene group, apyrenylene group, and the like can be given. As the substituent, analkyl group having 1 to 10 carbon atoms, an alkoxy group having 1 to 10carbon atoms, a cyano group, and the like can be given. Theelectron-transporting compound is preferably one from which a thin filmcan be formed.

The following compounds can be given as specific examples of theelectron-transporting compound.

Furthermore, as materials used for the electron-injecting layer andelectron-transporting layer, the compounds shown by the followingformulas (A) to (F) may be used.

Nitrogen-containing heterocyclic ring derivatives shown by the formulas(A) and (B) wherein A²¹ to A²³ are independently a nitrogen atom or acarbon atom;

Ar²¹ is a substituted or unsubstituted aryl group having 6 to 60 ringcarbon atoms or a substituted or unsubstituted heteroaryl group having 3to 60 ring carbon atoms; Ar²² is a hydrogen atom, a substituted orunsubstituted aryl group having 6 to 60 ring carbon atoms, a substitutedor unsubstituted heteroaryl group having 3 to 60 ring carbon atoms, asubstituted or unsubstituted alkyl group having 1 to 20 carbon atoms, asubstituted or unsubstituted alkoxy group having 1 to 20 carbon atoms,or a divalent group of these; provided that one of Ar²¹ and Ar²² is asubstituted or unsubstituted condensed ring group having 10 to 60 ringcarbon atoms, a substituted or unsubstituted monohetero condensed ringgroup having 3 to 60 ring carbon atoms, or a divalent group of these;

Ar²³ is a substituted or unsubstituted arylene group having 6 to 60carbon atoms or a substituted or unsubstituted heteroarylene grouphaving 3 to 60 carbon atoms;

L¹¹, L¹² and L¹³ are independently a single bond, a substituted orunsubstituted arylene group having 6 to 60 ring carbon atoms, asubstituted or unsubstituted heteroarylene group having 3 to 60 ringcarbon atoms or a substituted or unsubstituted fluorenylene group;

R¹²¹ and R¹²² are independently a hydrogen atom, a substituted orunsubstituted aryl group having 6 to 60 ring carbon atoms, a substitutedor unsubstituted heteroaryl group having 3 to 60 ring carbon atoms, asubstituted or unsubstituted alkyl group having 1 to 20 carbon atoms, ora substituted or unsubstituted alkoxy group having 1 to 20 carbon atoms,and n is an integer of 0 to 5, provided that, when n is an integer of 2or more, a plurality of R¹²¹s and R¹²²s may be the same or different;adjacent R¹²¹s and R¹²²s may be bonded to form a carbocyclic aliphaticring or a carbocyclic aromatic ring;

R¹²³ is a hydrogen atom, a substituted or unsubstituted aryl grouphaving 6 to 60 ring carbon atoms, a substituted or unsubstitutedheteroaryl group having 3 to 60 ring carbon atoms, a substituted orunsubstituted alkyl group having 1 to 20 carbon atoms, a substituted orunsubstituted alkoxy group having 1 to 20 carbon atoms or-L¹¹-Ar²¹—Ar²².

A nitrogen-containing heterocyclic derivative shown by the formula (C):HAr-L¹⁴-Ar²⁴—Ar²⁵  (C)wherein HAr is a nitrogen-containing heterocyclic ring with 3 to 40carbon atoms which may have a substituent; L¹⁴ is a single bond, anarylene group with 6 to 60 carbon atoms which may have a substituent, aheteroarylene group with 3 to 60 carbon atoms which may have asubstituent or a fluorenylene group which may have a substituent; Ar²⁴is a divalent aromatic hydrocarbon group with 6 to 60 carbon atoms whichmay have a substituent; and Ar²⁵ is an aryl group with 6 to 60 carbonatoms which may have a substituent or a heteroaryl group with 3 to 60carbon atoms which may have a substituent.

Silacyclopentadiene derivatives shown by the above formula (D) whereinX¹¹ and Y¹¹ are independently a saturated or unsaturated hydrocarbongroup having 1 to 6 carbon atoms, an alkoxy group, an alkenyloxy group,an alkynyloxy group, a hydroxyl group, a substituted or unsubstitutedaryl group, or a substituted or unsubstituted hetero ring, or X¹¹ andY¹¹ are bonded to form a saturated or unsaturated ring, and R¹²⁵ to R¹²⁸are independently a hydrogen atom, a halogen atom, a substituted orunsubstituted aryl group having 1 to 6 carbon atoms, an alkoxy group, anaryloxy group, a perfluoroalkyl group, a perfluoroalkoxy group, an aminogroup, an alkylcarbonyl group, an arylcarbonyl group, an alkoxycarbonylgroup, an aryloxycarbonyl group, an azo group, an alkylcarbonyloxygroup, an arylcarbonyloxy group, an alkoxycarbonyloxy group, anaryloxycarbonyloxy group, a sulfinyl group, a sulfonyl group, a sulfanylgroup, a silyl group, a carbamoyl group, an aryl group, a heterocyclicgroup, an alkenyl group, an alkynyl group, a nitro group, a formylgroup, a nitroso group, a formyloxy group, an isocyano group, a cyanategroup, an isocyanate group, a thiocyanate group, an isothiocyanategroup, or a cyano group, or adjacent groups of R¹²⁵ to R¹²⁸ form asubstituted or unsubstituted condensed ring.

Borane derivatives shown by the above formula wherein R¹³¹ to R¹³⁸ andZ² are independently a hydrogen atom, a saturated or unsaturatedhydrocarbon group, an aromatic group, a heterocyclic group, asubstituted amino group, a substituted boryl group, an alkoxy group, oran aryloxy group, X¹², Y¹², and Z¹ are independently a saturated orunsaturated hydrocarbon group, an aromatic group, a heterocyclic group,a substituted amino group, an alkoxy group, or an aryloxy group, thesubstituents for Z¹ and Z² may be bonded to form a condensed ring, n isan integer of 1 to 3, provided that the Z¹s may differ when n is 2 ormore, and a case in which n is 1, X¹², Y¹², and R¹³² are methyl groups,and R¹³⁸ is a hydrogen atom or a substituted boryl group, and a case inwhich n is 3 and Z¹ is a methyl group are excluded.

wherein Q¹ and Q² are independently ligands shown by the followingformula (G) and L¹⁵ is a halogen atom, a substituted or unsubstitutedalkyl group, a substituted or unsubstituted cycloalkyl group, asubstituted or unsubstituted aryl group, a substituted or unsubstitutedheterocyclic group, —OR′ (R′ is a hydrogen atom, a substituted orunsubstituted alkyl group, a substituted or unsubstituted cycloalkylgroup, a substituted or unsubstituted aryl group, or a substituted orunsubstituted heterocyclic group) or a ligand shown by —O—Ga-Q³(Q⁴) (Q³and Q⁴ have the same meanings as Q¹ and Q²).

wherein rings A²⁴ and A²⁵ are a 6-membered aryl ring structure which mayhave a substituent, and are condensed to each other.

The metal complexes have the strong nature of an n-type semiconductorand large ability of injecting electrons. Furthermore, the energygenerated at the time of forming a complex is small so that a metal isthen strongly bonded to ligands in the complex formed and thefluorescent quantum efficiency becomes large as the emitting material.

Specific examples of the substituents for the rings A²⁴ and R²⁵ formingthe ligand of the above formula (G) include halogen atoms such aschlorine, bromine, iodine, and fluorine, substituted or unsubstitutedalkyl groups such as a methyl group, ethyl group, propyl group, butylgroup, sec-butyl group, tert-butyl group, pentyl group, hexyl group,heptyl group, octyl group, stearyl group, and trichloromethyl group,substituted or unsubstituted aryl groups such as a phenyl group,naphthyl group, 3-methylphenyl group, 3-methoxyphenyl group,3-fluorophenyl group, 3-trichloromethylphenyl group,3-trifluoromethylphenyl group, and 3-nitrophenyl group, substituted orunsubstituted alkoxy groups such as a methoxy group, n-butoxy group,tert-butoxy group, trichloromethoxy group, trifluoroethoxy group,pentafluoropropoxy group, 2,2,3,3-tetrafluoropropoxy group,1,1,1,3,3,3-hexafluoro-2-propoxy group, and 6-(perfluoroethyl)hexyloxygroup, substituted or unsubstituted aryloxy groups such as a phenoxygroup, p-nitrophenoxy group, p-tert-butylphenoxy group, 3-fluorophenoxygroup, pentafluorophenyl group, and 3-trifluoromethylphenoxy group,substituted or unsubstituted alkylthio groups such as a methylthiogroup, ethylthio group, tert-butylthio group, hexylthio group, octylthiogroup, and trifluoromethylthio group, substituted or unsubstitutedarylthio groups such as a phenylthio group, p-nitrophenylthio group,p-tert-butylphenylthio group, 3-fluorophenylthio group,pentafluorophenylthio group, and 3-trifluoromethylphenylthio group, acyano group, a nitro group, an amino group, mono- or di-substitutedamino groups such as a methylamino group, diethylamino group, ethylaminogroup, diethylamino group, dipropylamino group, dibutylamino group, anddiphenylamino group, acylamino groups such as a bis(acetoxymethyl)aminogroup, bis(acetoxyethyl)amino group, bis(acetoxypropyl)amino group, andbis(acetoxybutyl)amino group, a hydroxyl group, a siloxy group, an acylgroup, substituted or unsubstituted carbamoyl groups such as a carbamoylgroup, methylcarbamoyl group, dimethylcarbamoyl group, ethylcarbamoylgroup, diethylcarbamoyl group, propylcarbamoyl group, butylcarbamoylgroup, and phenylcarbamoyl group, a carboxylic acid group, a sulfonicacid group, an imide group, cycloalkyl groups such as a cyclopentanegroup and a cyclohexyl group, aryl groups such as a phenyl group,naphthyl group, biphenyl group, anthryl group, phenanthryl group,fluorenyl group, and pyrenyl group, heterocyclic groups such as apyridinyl group, pyrazinyl group, pyrimidinyl group, pyridazinyl group,triathyl group, indolinyl group, quinolinyl group, acridinyl group,pyrrolidinyl group, dioxanyl group, piperidinyl group, morpholidinylgroup, piperazinyl group, triathinyl group, carbazolyl group, furanylgroup, thiophenyl group, oxazolyl group, oxadiazolyl group,benzooxazolyl group, thiazolyl group, thiadiazolyl group, benzothiazolylgroup, triazolyl group, imidazolyl group, benzoimidazolyl group, and thelike. The above substituents may be bonded to form a six-membered arylring or heterocyclic ring.

A preferred embodiment of the invention is a device containing areducing dopant in an electron-transporting region or in an interfacialregion between the cathode and the organic layer. The reducing dopant isdefined as a substance which can reduce an electron-transportingcompound. Accordingly, various substances which have given reducingproperties can be used. For example, at least one substance can bepreferably used which is selected from the group consisting of alkalimetals, alkaline earth metals, rare earth metals, alkali metal oxides,alkali metal halides, alkaline earth metal oxides, alkaline earth metalhalides, rare earth metal oxides, rare earth metal halides, alkali metalorganic complexes, alkaline earth metal organic complexes, and rareearth metal organic complexes.

More specific examples of the preferred reducing dopants include atleast one alkali metal selected from the group consisting of Li (workfunction: 2.9 eV), Na (work function: 2.36 eV), K (work function: 2.28eV), Rb (work function: 2.16 eV) and Cs (work function: 1.95 eV), and atleast one alkaline earth metal selected from the group consisting of Ca(work function: 2.9 eV), Sr (work function: 2.0 to 2.5 eV), and Ba (workfunction: 2.52 eV). A reducing dopant having a work function of 2.9 eVor less is particularly preferable.

Among these, a more preferable reducing dopant is at least one alkalimetal selected from the group consisting of K, Rb and Cs. Even morepreferable is Rb or Cs. Most preferable is Cs.

These alkali metals are particularly high in reducing ability. Thus, theaddition of a relatively small amount thereof to an electron-injectingzone improves the luminance of the organic EL device and make thelifetime thereof long. As a reducing agent having a work function of 2.9eV or less, combinations of two or more alkali metals are preferable,particularly combinations including Cs, such as Cs and Na, Cs and K, Csand Rb, or Cs, Na and K are preferable.

The combination containing Cs makes it possible to exhibit the reducingability efficiently. The luminance of the organic EL device can beimproved and the lifetime thereof can be made long by the additionthereof to its electron-injecting zone.

In the invention, an electron-injecting layer made of an insulator or asemiconductor may further be provided between a cathode and an organiclayer. By forming the electron-injecting layer, a current leakage can beeffectively prevented and electron-injecting properties can be improved.

As the insulator, at least one metal compound selected from the groupconsisting of alkali metal calcogenides, alkaline earth metalcalcogenides, halides of alkali metals and halides of alkaline earthmetals can be preferably used. When the electron-injecting layer isformed of the alkali metal calcogenide or the like, the injection ofelectrons can be preferably further improved.

Specifically preferable alkali metal calcogenides include Li₂O, LiO,Na₂S, Na₂Se and NaO and preferable alkaline earth metal calcogenidesinclude CaO, BaO, SrO, BeO, BaS and CaSe. Preferable halides of alkalimetals include LiF, NaF, KF, CsF, LiCl, KCl and NaCl. Preferable halidesof alkaline earth metals include fluorides such as CaF₂, BaF₂, SrF₂,MgF₂ and BeF₂ and halides other than fluorides.

Semiconductors forming an electron-transporting layer include one orcombinations of two or more of oxides, nitrides, and oxidized nitridescontaining at least one element of Ba, Ca, Sr, Yb, Al, Ga, In, Li, Na,Cd, Mg, Si, Ta, Sb and Zn.

An inorganic compound forming an electron-transporting layer ispreferably a microcrystalline or amorphous insulating thin film. Whenthe electron-transporting layer is formed of the insulating thin films,more uniformed thin film is formed whereby pixel defects such as a darkspot are decreased.

Examples of such an inorganic compound include the above-mentionedalkali metal calcogenides, alkaline earth metal calcogenides, halides ofalkali metals, and halides of alkaline earth metals.

(Cathode)

For the cathode, the following may be used: an electrode substance madeof a metal, an alloy or an electroconductive compound, or a mixturethereof which has a small work function (for example, 4 eV or less).Specific examples of the electrode substance include sodium,sodium-potassium alloy, magnesium, lithium, magnesium/silver alloy,aluminum/aluminum oxide, aluminum/lithium alloy, indium, and rare earthmetals.

This cathode can be formed by making the electrode substances into athin film by vapor deposition, sputtering or some other method.

In the case where light is emitted from the emitting layer through thecathode, the cathode preferably has a light transmittance of larger than10%.

The sheet resistance of the cathode is preferably several hundred Ω/□ orless, and the film thickness thereof is usually from 10 nm to 1 μm,preferably from 50 to 200 nm.

(Insulating Layer)

In the organic EL device, pixel defects based on leakage or a shortcircuit are easily generated since an electric field is applied to theultrathin film. In order to prevent this, it is preferred to insert aninsulative thin layer between the pair of electrodes.

Examples of the material used in the insulating layer include aluminumoxide, lithium fluoride, lithium oxide, cesium fluoride, cesium oxide,magnesium oxide, magnesium fluoride, calcium oxide, calcium fluoride,cesium carbonate, aluminum nitride, titanium oxide, silicon oxide,germanium oxide, silicon nitride, boron nitride, molybdenum oxide,ruthenium oxide, and vanadium oxide.

A mixture or laminate thereof may be used.

(Example of Fabricating Organic EL Device)

Using the above-mentioned materials, an organic EL device can befabricated by forming an anode, a hole-injecting layer, ahole-transporting layer, an emitting layer, an electron-injecting layeror the like, followed by formation of a cathode. The organic EL devicecan be fabricated in the order reverse to the above, i.e., the orderfrom a cathode to an anode.

An example of the fabrication of the organic EL device will be describedbelow which has a structure wherein the following are successivelyformed on a transparent substrate: anode/hole-injectinglayer/hole-transporting layer/emitting layer/electron-transportinglayer/cathode.

First, a thin film made of an anode material is formed into a thicknessof 1 μm or less, preferably 10 to 200 nm on an appropriate transparentsubstrate by vapor deposition, sputtering or some other method, therebyforming an anode.

Next, a hole-injecting layer and a hole-transporting layer are formed onthis anode. As described above, these layers can be formed by vacuumdeposition, spin coating, casting, LB technique, or some other method.Vapor vacuum deposition is preferred since a homogenous film is easilyobtained and pinholes are not easily generated.

In the case where the hole-injecting layer and the hole-transportinglayer are formed by vapor vacuum deposition, conditions for thedeposition vary depending upon the compound used, the desired crystalstructure or recombining structure of the hole-injecting layer and thehole-transporting layer, and others. In general, the conditions arepreferably selected from the following: deposition source temperature of50 to 450° C., vacuum degree of 10⁻⁷ to 10⁻³ torr, vapor deposition rateof 0.01 to 50 nm/second, substrate temperature of −50 to 300° C., andfilm thickness of 1 nm to 5 μm.

Next, an emitting layer is formed on the hole-transporting layer. Theemitting layer can also be formed by making a desired organicluminescent material into a thin film by vacuum vapor deposition,sputtering, spin coating, casting or some other method. Vacuum vapordeposition is preferred since a homogenous film is easily obtained andpinholes are not easily generated. In the case where the emitting layeris formed by vapor vacuum deposition, conditions for the deposition,which vary depending on a compound used, can be generally selected fromconditions similar to those for the hole-transporting layer.

Next, an electron-transporting layer is formed on this emitting layer.Like the hole-transporting layer and the emitting layer, the layer ispreferably formed by vacuum vapor deposition because a homogenous filmis required. Conditions for the deposition can be selected fromconditions similar to those for the hole-transporting layer and theemitting layer.

Lastly, a cathode is stacked thereon to obtain an organic EL device.

The cathode is made of a metal, and vapor deposition or sputtering maybe used. However, vapor vacuum deposition is preferred in order toprotect underlying organic layers from being damaged when the cathodefilm is formed.

For the organic EL device fabrication that has been described above, itis preferred that the formation from the anode to the cathode iscontinuously carried out, using only one vacuuming operation.

The method for forming each of the layers in the organic EL device ofthe invention is not particularly limited. Specifically, the layers canbe formed by a known method, such as vacuum deposition, molecular beamdeposition (MBE method), or coating method such as dipping, spincoating, casting, bar coating and roll coating using a solution obtainedby dissolving materials in a solvent.

The film thickness of each of the organic layers in the organic ELdevice of the invention is not particularly limited. In general, defectssuch as pinholes are easily generated when the film thickness is toosmall. Conversely, when the film thickness is too large, a high appliedvoltage becomes necessary, leading to low efficiency. Usually, the filmthickness is preferably in the range of several nanometers to onemicrometer.

The organic EL device emits light when applying a voltage betweenelectrodes. If a DC voltage is applied to the organic EL device,emission can be observed when the polarities of the anode and thecathode are positive and negative, respectively, and a DC voltage of 5to 40 V is applied. When a voltage with an opposite polarity is applied,no electric current flows and hence, emission does not occur. If an ACvoltage is applied, uniform emission can be observed only when thecathode and the anode have a positive polarity and a negative polarity,respectively. The waveform of the AC applied may be arbitrary.

EXAMPLES

The material for an organic EL device and the organic EL device of theinvention will be described in more detail with reference to Examples,which should not be construed as limiting the scope of the invention.

The structures of the compounds used in the examples and comparativeexamples are shown below.

Example 1 Synthesis of a Compound Shown by the Formula (A-1)

The compound (A-1) was synthesized by the following synthesis scheme.

(1) Synthesis of Intermediate A

2.2 g of 3,9-dibromo-indenofluorenedione prepared according to asynthesis method described in a document (Organic Letters, vol. 7, issue19, page 4229) was mixed with 2.1 g of 4-(trifluoromethyl)phenylboronicacid, 0.14 g of tris(dibenzylideneacetone)dipalladium (0), 0.091 g oftris-t-butylphosphine, 1.9 g of potassium fluoride and 40 ml of tolueneunder argon stream. The mixture was stirred with reflux for 8 hours.After cooling, the reaction liquid was filtered and a reddish purplesolid was washed with water and methanol. As a result of massspectroscopy of the resulting solid, a peak was observed at M/Z=570.

(2) Synthesis of Compound (A-1)

2.0 g of the intermediate A which had been synthesized before wasdissolved in 100 ml of methylene chloride with stirring. After makingthe atmosphere of the inside of the flask argon, the temperature of thesolution was cooled to −10° C. or less with a salt-ice bath. 2.7 g oftitanium tetrachloride was added to the solution. Thereafter, a mixtureof 8.2 g of bis(trimethylsilyl)carbodiimide and 40 ml of methylenechloride was added dropwise. After the dropwise addition, cooling wascontinued for 1 hour. Then, the mixture was stirred at room temperaturefor 4 hours, and stirred with reflux for a further 2 hours. Aprecipitated reddish purple solid was filtered and washed with methanol.

After purification through sublimation, 1.4 g of the compound wasobtained.

The IR of this compound was measured. The results showed that theabsorption of a carbonyl group disappeared and the absorption of a cyanogroup was newly observed at 2183 cm⁻¹. As a result of mass spectroscopy,a peak was observed at M/Z=618.

The compound was dissolved in acetonitrile with a concentration of 0.01mol/l, and the reduction potential thereof was measured by cyclicvoltammetry by using tetrabutylammonium perchlorate (TBAP) as asupporting electrolyte, a glassy carbon electrode as an activeelectrode, a platinum electrode as a counter electrode and asilver-silver chloride electrode as a reference electrode. The reductionpotential of the compound (A-1) at a sweep rate of 0.1V/s was −0.3 V.

As a reference material, ferrocene (hereinafter referred to as “Fc”) wasmeasured similarly. The first oxidation potential thereof was 0.5V.Taking this oxidation potential of ferrocene as a reference, thereduction potential of the compound (A-1) was −0.8 V(vs Fc⁺/Fc).

Example 2 Synthesis of a Compound Shown by the Formula (A-2)

1.5 g of the intermediate A which had been synthesized before, 0.35 g ofmalononitrile and 80 ml of pyridine were added, and the resultant washeated with stirring at 90° C. for 8 hours. After cooling, the solidmatter was filtered, washed with water and methanol, and dried underreduced pressure. Thereafter, purification through sublimation wasperformed to obtain 1.2 g of a purple crystal.

The IR of this compound was measured. The results showed that theabsorption of a carbonyl group disappeared and the absorption of a cyanogroup was newly observed at 2222 cm⁻¹. As a result of mass spectroscopy,a peak was observed at M/Z=666.

In the same manner as in Example 1, the reduction potential of thiscompound was measured by cyclic voltammetry. When the first oxidationpotential of ferrocene (hereinafter referred to as the “Fc”) was takenas a reference potential, the reduction potential of the compound (A-2)was −0.75 V (vs Fc⁺/Fc)

Example 3 Synthesis of a Compound Shown by the Formula (A-15)

The compound (A-15) was synthesized from the compound shown by thefollowing formula B.

In the synthesis of the compound (A-1) in Example 1, the same procedurewas performed except that the intermediate A was changed to 1.1 g of thecompound B, whereby 0.8 g of an orange solid as compound (A-15) wasobtained.

The IR of this compound was measured. The results showed that theabsorption of a carbonyl group disappeared and the absorption of a cyanogroup was newly observed at 2181 cm⁻¹. As a result of mass spectroscopy,a peak was observed at M/Z=366.

The reduction potential of this compound was measured in the same manneras in Example 1 and found to be −0.7V (vs Fc⁺/Fc).

Example 4 Synthesis of a Compound Shown by the Formula (A-16)

In the synthesis of the compound (A-2) in Example 2, the same procedurewas performed except that the intermediate A was changed to 0.8 g of thecompound B, whereby 0.6 g of an orange solid as the compound (A-16) wasobtained.

The IR of this compound was measured. The results showed that theabsorption of a carbonyl group disappeared and the absorption of a cyanogroup was newly observed at 2223 cm⁻¹. As a result of mass spectroscopy,a peak was observed at M/Z=414.

The reduction potential of this compound was measured in the same manneras in Example 1 and found to be −0.7V (vs Fc⁺/Fc).

Example 5 Synthesis of a Compound Shown by the Formula (A-3)

(1) Synthesis of Intermediate C

2.4 g of 3,9-dibromo-indenofluorenedione was mixed with 3.4 g of3,5-bis(trifluoromethyl)phenylboronic acid, 0.23 g oftetraxis(triphenylenephosphine)palladium (0), 20 ml of 2M sodiumcarbonate and 130 ml of toluene under argon stream. The mixture wasstirred with reflux for 12 hours. After cooling, the reaction liquid wasfiltered, washed with water and methanol, whereby 3.5 g of a reddishpurple solid as an intermediate A was obtained.

As a result of mass spectroscopy of the resulting solid, a peak wasobserved at M/Z=706.

(2) Synthesis of Compound (A-3)

In the synthesis of the compound (A-1) in Example 1, the same procedurewas performed except that the intermediate A was changed to 2.4 g of theintermediate C, whereby 1.5 g of compound (A-3) was obtained.

The IR of this compound was measured. The results showed that theabsorption of a carbonyl group disappeared and the absorption of a cyanogroup was newly observed at 2182 cm⁻¹. As a result of mass spectroscopy,a peak was observed at M/Z=754.

The reduction potential of this compound was measured in the same manneras in Example 1 and found to be −0.65V (vs Fc⁺/Fc).

Example 6 Synthesis of a Compound Shown by the Formula (A-4)

In the synthesis of the compound (A-2) in Example 2, the same procedurewas performed except that the intermediate A was changed to 1.8 g of theintermediate C, whereby 1.2 g of an orange solid as compound (A-4) wasobtained.

The IR of this compound was measured. The results showed that theabsorption of a carbonyl group disappeared and the absorption of a cyanogroup was newly observed at 2223 cm⁻¹. As a result of mass spectroscopy,a peak was observed at M/Z=802.

The reduction potential of this compound was measured in the same manneras in Example 1 and found to be −0.6V (vs Fc⁺/Fc).

Example 7 Synthesis of a Compound Shown by the Formula (A-38)

(1) Synthesis of Intermediate D

3.0 g of 3,9-dibromo-indenofluorenedione was mixed with 3.3 g of4-fluoro-3-(trifluoromethyl)phenylboronic acid, 0.29 g oftetraxis(triphenylenephosphine)palladium (0), 25 ml of 2M sodiumcarbonate and 160 ml of toluene under argon stream. The mixture wasstirred with reflux for 12 hours. After cooling, the reaction liquid wasfiltered, washed with water and methanol, whereby 3.7 g of a reddishpurple solid as an intermediate D was obtained. As a result of massspectroscopy of the resulting solid, a peak was observed at M/Z=606.

(2) Synthesis of Compound (A-38)

2.7 g of the intermediate D which had been synthesized before, 0.73 g ofmalononitrile and 67 ml of pyridine were added, and the resultant washeated with stirring at 80° C. for 7 hours. The solid matter wasfiltered, washed with water and methanol, and dried under reducedpressure. Thereafter, purification through sublimation was performed toobtain 1.7 g of a purple crystal as compound (A-38).

The IR of this compound was measured. The results showed that theabsorption of a carbonyl group disappeared and the absorption of a cyanogroup was newly observed at 2185 cm⁻¹. As a result of mass spectroscopy,a peak was observed at M/Z=702.

The reduction potential of this compound was measured in the same manneras in Example 1 and found to be −0.75V (vs Fc⁺/Fc).

[Organic EL Device]

Example 8

A glass substrate of 25 mm by 75 mm by 1.1 mm thick with an ITOtransparent electrode (GEOMATEC CO., LTD.) was subjected to ultrasoniccleaning with isopropyl alcohol for 5 minutes, and cleaned withultraviolet rays and ozone for 30 minutes.

The cleaned glass substrate having the transparent electrode lines wasthen secured to a substrate holder of an apparatus for vacuumdeposition. First, the compound shown by the formula (A-2) synthesizedin Example 2 and a compound shown by the following formula (C-1) wereformed into a 60 nm-thick film, at a molar ratio of 2:98, on the glasssubstrate on which the transparent electrode lines were formed so as tocover the transparent electrodes. The film of the compound mixturefunctioned as a hole-injecting layer.

Subsequently, a 20 nm-thick film of a compound shown by the followingformula (HTM-1) was formed on the above-obtained film of the compoundmixture. This film functioned as a hole-transporting layer.

Further, EM1 with a thickness of 40 nm was deposited thereon to form afilm. Simultaneously, as the emitting molecule, the following compoundD1 having a styryl group was deposited such that the weight ratio of EM1and D1 became 40:2. This film functioned as an emitting layer.

A 10 nm-thick Alq film was formed on the above-obtained film. The filmserved as an electron-injecting layer. Then, Li as a reductive dopant(Li source: manufactured by SAES Getters Co., Ltd.) and Alq wereco-deposited, whereby an Alq:Li film (film thickness: 10 nm) was formedas an electron-injecting layer (cathode). Metal aluminum was depositedon the Alq:Li film to form a metallic cathode, whereby an organic ELemitting device was fabricated.

The organic EL device was evaluated by measuring a driving voltage at acurrent density of 10 mA/cm² and a half life of luminance at an initialluminance of 1,000 nits, at room temperature, and with a DC constantpower supply. The results obtained are shown in Table 1.

Example 9

An organic EL device was fabricated and evaluated in the same manner asin Example 8, except that the compound (A-4) alone which had beensynthesized in Example 6 was used in the hole-injecting layer, thethickness thereof was rendered 10 nm, and the thickness of thehole-translating layer (HTM-1) was changed to 70 nm. The results areshown in Table 1.

Example 10

An organic EL device was fabricated and evaluated in the same manner asin Example 9, except that the compound (A-38) alone which had beensynthesized in Example 7 was used in the hole-injecting layer. Theresults are shown in Table 1.

Example 11

An organic EL device was fabricated and evaluated in the same manner asin Example 9, except that the compound (A-3) alone which had beensynthesized in Example 5 was used in the hole-injecting layer. Theresults are shown in Table 1.

Example 12

An organic EL device was fabricated and evaluated in the same manner asin Example 9, except that that the compound (A-1) alone which had beensynthesized in Example 1 was used in the hole-injecting layer. Theresults are shown in Table 1.

Example 13

An organic EL device was fabricated and evaluated in the same manner asin Example 9, except that the compound (A-2) alone which had beensynthesized in Example 2 was used in the hole-injecting layer. Theresults are shown in Table 1.

Comparative Example 1

An organic EL device was fabricated and evaluated in the same manner asin Example 8, except that the compound shown by the formula (C-1) alonewas used in the hole-injecting layer.

The results are shown in Table 1.

In the case of the organic EL device of Comparative Example 1, voltagewas increased by 1V or more after 5,000 hour-driving. In contrast, inorganic EL devices of Examples 8 to 13, voltage was increased by 0.5V orless, which showed that a voltage increase was suppressed in Examples 8to 13.

Comparative Example 2

An organic EL device was fabricated and evaluated in the same manner asin Example 9, except that the compound B(2,7-difluoroindenofluorenedione) alone was used for forming ahole-injecting layer. The results showed that the resulting organic ELdevice suffered a large amount of leak current, and uniform emissioncould not be obtained. The reason therefor is thought to be thecrystallization of the compound B, the shortage of an acceptor due tothe quinone structure, or the like.

TABLE 1 Materials constituting Driving Half the hole-injecting layervoltage (V) life (hr) Example 8 Compound (A-2) 6.2 6,600 Compound (C-1)Example 9 Compound (A-4) 5.8 7,600 Example 10 Compound (A-38) 5.8 7,400Example 11 Compound (A-3) 6.2 7,500 Example 12 Compound (A-1) 5.9 7,400Example 13 Compound (A-2) 6.1 6,800 Com. Ex. 1 Compound (C-1) 6.6 5,000

INDUSTRIAL APPLICABILITY

The material for an organic EL device of the invention is suitable as aconstitution material of an organic EL device, in particular, ahole-transporting layer or a hole-injecting layer. The material for anorganic EL device of the invention can also be used as acharge-transporting material of an electrophotographic photoreceptor.

The organic EL device of the invention can be suitably used as a lightsource such as a planar emitting body and backlight of a display, adisplay part of a portable phone, PDA, a car navigator, or aninstruction panel of an automobile, an illuminator, and the like.

The contents of all the documents in this specification are incorporatedherein by reference.

The invention claimed is:
 1. An organic electroluminescence device,comprising an organic thin film layer between an anode and a cathode,wherein: the organic thin film layer comprises a multilayer stack inwhich a hole-injecting layer, a hole-transporting layer, an emittinglayer and an electron-transporting layer are stacked sequentially fromthe anode; the hole-injecting layer comprises a material for an organicelectroluminescence device comprising an indenofluorenedione derivativerepresented by any of formulae (IIa), (IIb), (IIc) and (III):

R¹¹ to R⁵⁰ represent, independently of one another, a hydrogen atom, analkyl group optionally substituted by a substituent, an aryl groupoptionally substituted by a substituent, an alkoxy group optionallysubstituted by a substituent, an aryloxy group optionally substituted bya substituent, a fluoroalkyl group optionally substituted by asubstituent, or a heterocycle optionally substituted by a substituent,with proviso that all of R¹¹ to R⁵⁰ may not be a hydrogen atom; and R¹¹to R⁵⁰ are optionally bonded to each other to form a ring.
 2. Theorganic electroluminescence device according to claim 1, wherein atleast one substituent selected from the group consisting of a halogenatom, a cyano group, an alkyl group, an aryl group, a fluoroalkyl group,and a heterocycle is present.
 3. An organic electroluminescence device,comprising an organic thin film layer between an anode and a cathode,wherein: the organic thin film layer comprises a multilayer stack inwhich a hole-injecting layer, a hole-transporting layer, an emittinglayer and an electron-transporting layer are stacked sequentially fromthe anode; and the hole-injecting layer comprises a material for anorganic electroluminescence device comprising a compound represented byany of formulae (A-1) to (A-89):